The only thing I can think of are tats for the three Chosen. One of my favorite things to do is to commemorate major operations in the game(like the Blacksite, Chosen strongholds, ect.) with the soldiers involved in those ops getting a tattoo that represents it.

I did Electric Alien, for instance, on the whole team that hit the Blacksite(that same op had me accomplish the Skulljack Advent Officer objective, too, so it was a twofer), and a Shadow Wolf for the team that hit the Assassin's compound. I also put the Viper King design on the team that took out the Viper King.

So it'd be cool if Chosen ops could be commemorated with Chosen tattoos.